Compact filtration units with pleated filter elements are known, for example, from Swiss Patent No. 568,761 and from European Patent No. 0 154 845 A2. Swiss Patent No. 568,761 describes a compact filtration unit to be used as a blood filter which comprises a rectangular multi-component housing with coaxial fluid connectors that are separated from one another by a multi-layer pleated filter element. The pleated filter element is held at each of the two ends of its tapered pleats, between specially configured wall regions of the upper and lower housing halves and welded to them, and with two end faces is sealed by way of a sealant with a lateral closure in each case. Corresponding fluid-tight joints exist between the upper and lower halves and the two end plates of the housing. In all, a total of seven fluid-tight welds are present.
Commonly assigned European Patent No. 0 154 845 A2 discloses a round pleated filter element that has a specially designed seal flange adapted to be clamped in fluid-tight fashion between two housing halves by rivet-like fasteners, the housing halves being provided with annular channels on their periphery to accept sealant.
The principal drawbacks of both such prior art filtration units are their large number of components and large number of regions at which such components are joined in fluid-tight fashion to one another. In addition to being complex from the manufacturing standpoint, such devices often represent considerable sources of leaks which can result in premature failure of the filtration unit during use.
It is therefore an object of the invention to create, from a small number of components, a compact filtration unit with pleated filter elements which has a minimum of regions to be sealed.